#! /usr/bin/env python
# -*- coding: utf-8 -*-

# *************************************************************
#  Copyright (c) Huoty - All rights reserved
# 
#      Author: Huoty <sudohuoty@gmail.com>
#  CreateTime: 2016-11-07 16:34:03
# *************************************************************

from traitlets import HasTraits, TraitError, Int, Bool, validate

class Parity(HasTraits):
    value = Int()
    parity = Int()

    @validate('value')
    def _valid_value(self, proposal):
        if proposal['value'] % 2 != self.parity:
            raise TraitError('value and parity should be consistent')
        return proposal['value']

    @validate('parity')
    def _valid_parity(self, proposal):
        parity = proposal['value']
        if parity not in [0, 1]:
            raise TraitError('parity should be 0 or 1')
        if self.value % 2 != parity:
            raise TraitError('value and parity should be consistent')
        return proposal['value']

parity_check = Parity(value=2)

# Changing required parity and value together while holding cross validation
with parity_check.hold_trait_notifications():
    parity_check.value = 1
    parity_check.parity = 1 

    #parity_check.value = 1.1

parity_check.value = 1.1

